Selling inestment house

If you sell an investment house within a year of buying it do you still have to pay CGT if there is a profit

Yes unfortunately.

In fact some suggest that the sale of an investment property within a year of purchase is carring on a trade and therefore liable to Income Tax.
Most investors put long term finance in place and ensure that properties are let for longer that 1 year in order to "qualify" for CGT.
If this is your only property I don't think you will have a problem but if you did and same again I think that you would be assessable to Income Tax.

Investment property is for the long haul. Rarely makes sense to sell quickly as you have to take into account stamp duty paid on the purchase and legal fees etc. These usually eat up and increase in value for the first couple of years